CO2 recovery system

ABSTRACT

A CO2 recovery system used in a vehicle includes a CO2 recovery device recovering CO2 contained in inflowing gas; and a flow rate control device controlling flow rates of gases present in a plurality of different regions of the vehicle flowing into the CO2 recovery device. The gases present at the plurality of different regions include at least any two among air at an outside of the vehicle, air at an inside of the vehicle, and exhaust gas discharged from a body of an internal combustion engine of the vehicle.

RELATED APPLICATIONS

The present application claims priority of Japanese Patent ApplicationNo. 2019-109015, filed Jun. 11, 2019, the disclosure of which is herebyincorporated by reference herein in its entirety.

FIELD

The present disclosure relates to a CO₂ recovery system.

BACKGROUND

Known in the past has been a CO₂ recovery system used for a vehiclehaving a CO₂ recovery device recovering CO₂ contained in inflowingexhaust gas (for example, PTL 1). In particular, in the CO₂ recoverysystem described in PTL 1, the exhaust gas discharged from an internalcombustion engine mounted in a vehicle is supplied to the CO₂ recoverydevice, and as a result the CO₂ in the exhaust gas is recovered by theCO₂ recovery device.

CITATIONS LIST Patent Literature

-   [PTL 1] JP 2014-504695 A

SUMMARY Technical Problem

CO₂ is contained not only in the exhaust gas, but also in the air at theoutside of a vehicle or the air at the inside of a vehicle. Therefore,it may also be considered to recover the CO₂ in the air at the inside ofand outside of a vehicle. However, in the CO₂ recovery system describedin PTL 1, nothing other than the exhaust gas of the internal combustionengine was supplied to the CO₂ recovery device. Accordingly, it was notpossible to recover CO₂ from the air at the inside of and outside of thevehicle.

In view of the above technical problem, an object of the presentdisclosure is to provide a CO₂ recovery system able to recover CO₂ ingases present in a plurality of different regions of the vehicle.

Solution to Problem

The present invention has as its gist the following.

(1) A CO₂ recovery system used in a vehicle, comprising:

-   -   a CO₂ recovery device recovering CO₂ contained in inflowing gas;        and    -   a flow rate control device controlling flow rates of gases        present in a plurality of different regions of the vehicle        flowing into the CO₂ recovery device,    -   wherein the gases present at the plurality of different regions        include at least any two among air at an outside of the vehicle,        air at an inside of the vehicle, and exhaust gas discharged from        a body of an internal combustion engine of the vehicle.

(2) The CO₂ recovery system according to above (1), wherein the flowrate control device controls the flow rate of air at the outside of thevehicle flowing into the CO₂ recovery device, based on a CO₂concentration in the air at the outside of the vehicle.

(3) The CO₂ recovery system according to above (1) or (2), wherein theflow rate control device controls the flow rate of air at the inside ofthe vehicle flowing into the CO₂ recovery device, based on a CO₂concentration in the air at the inside of the vehicle.

(4) The CO₂ recovery system according to any one of above (1) to (3),wherein

-   -   the flow rate control device has a switching device arranged at        an upstream side of the CO₂ recovery device in a direction of        flow of the gas and a pump forcibly sending gases from a        plurality of different regions through the switching device to        the CO₂ recovery device, and    -   the switching device switches the gas to be flowed to the CO₂        recovery device among the gases present in the plurality of        different regions.

(5) The CO₂ recovery system according to above (4), wherein

-   -   the vehicle has an internal combustion engine having the body of        the internal combustion engine and an exhaust passage through        which exhaust gas discharged from the body of the internal        combustion engine flows,    -   the gases present at the plurality of different regions include        exhaust gas discharged from the body of the internal combustion        engine, and    -   the switching device communicates with the exhaust passage so        that exhaust gas can flow to the switching device from the        exhaust passage.

(6) The CO₂ recovery system according to above (5), wherein

-   -   a first connection passage communicating the exhaust passage        with the switching device is provided with a cooling device        cooling the gas, and    -   a second connection passage communicating an outside of the        vehicle with the switching device and a third connection passage        communicating an inside of the vehicle with the switching device        are not provided with cooling devices.

(7) The CO₂ recovery system according to above (5), wherein acommunication path communicating the switching device with the CO₂recovery device is provided with a cooling device cooling gas flowingthrough the communication path.

(8) The CO₂ recovery system according to any one of above (5) to (7),wherein the flow rate control device controls the flow rate of theexhaust gas, which is discharged from the body of the internalcombustion engine, flowing into the CO₂ recovery device, based on theCO₂ concentration in the exhaust gas flowing through the exhaustpassage.

(9) The CO₂ recovery system according to any one of above (5) to (8),wherein the flow rate control device is controlled so that when theinternal combustion engine is stopped, at least one of air at theoutside of the vehicle and air at the inside of the vehicle, flows intothe CO₂

(10) The CO₂ recovery system according to any one of above (4) to (9),wherein when the flow rate control device is controlled so that air atthe outside of the vehicle flows into the CO₂ recovery device, the pumpis controlled so that an output of the pump decreases, as the a runningspeed of the vehicle becomes faster.

(11) The CO₂ recovery system according to any one of above (1) to (10),wherein

-   -   the system further comprises an awakeness degree detection        device for detecting a degree of awakeness of a driver,    -   the CO₂ recovery device is configured to be able to return gas        discharged from the CO₂ recovery device to the inside of the        vehicle, and    -   when a degree of awakeness of the driver is lower than a        predetermined threshold value, the flow rate control device is        controlled so that the air at the inside of the vehicle flows        into the CO₂ recovery device and the gas discharged from the CO₂        recovery device is returned to the inside of the vehicle.

Advantageous Effects of Invention

According to the present disclosure, there is provided a CO₂ recoverysystem able to recover CO₂ in gases present in a plurality of differentregions of the vehicle.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view schematically showing a vehicle having a CO₂recovery system according to one embodiment.

FIG. 2 is a side view schematically showing a vehicle having a CO₂recovery system according to one embodiment.

FIG. 3 is a view schematically explaining the configuration of a CO₂recovery system.

FIG. 4 is a view showing a relationship between pump work performed by asuction pump and an amount of CO₂ reduction.

FIG. 5 is a flow chart showing a control routine in control in the CO₂recovery system.

FIG. 6 is a view schematically explaining the configuration of a CO₂recovery system according to a second embodiment.

FIG. 7 is a flow chart showing a control routine in control in the CO₂recovery system.

BRIEF DESCRIPTION OF DRAWINGS

Below, referring to the drawings, an embodiment will be explained indetail. Note that, in the following explanation, similar componentelements are assigned the same reference signs.

First Embodiment

Configuration of Vehicle

Referring to FIGS. 1 and 2, a vehicle mounting a CO₂ recovery systemaccording to one embodiment will be explained. FIG. 1 is a plan viewschematically showing a vehicle 1 having a CO₂ recovery system accordingto the embodiment. FIG. 2 is a side view schematically showing a vehicle1 having this CO₂ recovery system.

As shown in FIGS. 1 and 2, the vehicle 1 has an internal combustionengine 10 for driving the vehicle 1 and a CO₂ recovery system 20 forrecovering CO₂. Note that, in the present embodiment, the internalcombustion engine 10 is used as the power source for driving the vehicle1, but an electric motor may be used as the power source for driving thevehicle 1 in addition to the internal combustion engine 10 or instead ofthe internal combustion engine 10.

The internal combustion engine 10 has an engine body 11, exhaust pipe12, exhaust purification device 13, and muffler 14. The engine body 11is arranged in an engine compartment formed at the front of the vehicle1 (left side of FIGS. 1 and 2). The exhaust pipe 12 mainly extends underan underbody 2 of the vehicle 1 from the engine body 11 toward the backof the vehicle 1 in the front-back direction of the vehicle 1. Theexhaust purification device 13 and muffler 14 are provided at theexhaust pipe 12.

The engine body 11 generates power for driving the vehicle 1 by burningfuel at the inside. The exhaust gas generated due to combustion of fuelin the engine body 11 flows into the exhaust pipe 12.

The exhaust pipe 12 is connected through an exhaust manifold 15 to theengine body 11. The exhaust gas discharged from the engine body 11 flowsthrough the inside of the exhaust pipe 12. From the outlet of theexhaust pipe 12, exhaust gas is released to the atmosphere. The exhaustpipe 12 forms an exhaust passage through which exhaust gas dischargedfrom the engine body 11 flows.

The exhaust purification device 13 purifies the NOx, HC (hydrocarbons),CO, particulate, and other substances in the exhaust gas flowing intothe exhaust purification device 13. The exhaust purification device 13is, for example, a three-way catalyst, a NOx storage reduction catalyst,or a particulate filter. Note that, a plurality of exhaust purificationdevices 13 may also be provided at the exhaust pipe 12.

The muffler 14 causes the temperature and pressure of the exhaust gasflowing through the exhaust pipe 12 to decrease, to reduce the exhaustnoise. The muffler 14 is arranged at the downstream side of the exhaustpurification device 13 in the downstream direction of the exhaust gas.Note that, a plurality of the mufflers 14 may also be provided at theexhaust pipe 12.

Configuration of CO₂ Recovery System

The CO₂ recovery system 20 has a CO₂ recovery device 21, flow pathswitching device 22, suction pump 23, and cooling device 24.

The CO₂ recovery device 21 is a device for recovering the CO₂ in the gassupplied to the CO₂ recovery device 21. In the present embodiment, theCO₂ recovery device is arranged in or below luggage space positioned atthe back of the vehicle 1. Note that, the CO₂ recovery device 21 is aheavy object, therefore it is preferable to arrange it as low aspossible in the vertical direction in the luggage space.

The method of recovery of CO₂ in the gas by the CO₂ recovery device 21may be, for example, the physical adsorption method, physical absorptionmethod, chemical absorption method, cryogenic separation method, etc.

The physical adsorption method, for example, is a method of bringingactivated carbon, zeolite, or other solid adsorbent into contact with agas containing CO₂ to thereby make the CO₂ be adsorbed at the solidadsorbent, and heating (or reducing the pressure) to thereby make theCO₂ be desorbed from the solid adsorbent.

When employing the physical adsorption method, the CO₂ recovery device21 is, for example, configured as a container holding pellet shapedzeolite. By making the gas containing CO₂ flow through the container,the CO₂ is adsorbed by the zeolite.

The physical absorption method is a method of making an absorptionsolution, which is able to dissolve the CO₂ (for example methanol orN-methyl pyrrolidone), contact the gas containing CO₂ to physically makethe CO₂ be absorbed at a high pressure and low temperature, and heating(or reducing the pressure) the absorption solution to recover the CO₂from it.

When employing the physical absorption method, the CO₂ recovery device21 is, for example, configured as a container containing methanol. Bymaking the gas containing CO₂ flow through the methanol held in thecontainer, the CO₂ is absorbed by the methanol.

The chemical absorption method is a method of making an absorptionsolution, which is able to selectively dissolve the CO₂ (for example,amine or a potassium carbonate aqueous solution), contact the gascontaining CO₂ to make the CO₂ be absorbed in the absorption solution bya chemical reaction, and heating it thereby making the CO₂ be desorbedfrom the absorption solution.

When employing the chemical absorption method, the CO₂ recovery device21 is, for example, configured as a container holding amine. By makingthe gas containing CO₂ flow through the inside of the amine held in thecontainer, the CO₂ is absorbed by the amine.

In the present embodiment, in the CO₂ recovery device 21, the physicaladsorption method is employed as the method of recovery of the CO₂ inthe exhaust. Therefore, the CO₂ recovery device 21 is configured as acontainer holding pellet shaped zeolite.

The flow path switching device 22 is a device switching the type of thegas flowing into the CO₂ recovery device 21. In the present embodiment,the flow path switching device 22 is arranged in or below luggage spacepositioned at the back of the vehicle 1.

The flow path switching device 22 communicates through a communicationpath 31 with the CO₂ recovery device 21. Therefore, the gas flowing outfrom the flow path switching device 22 flows through the communicationpath 31 into the CO₂ recovery device 21. In other words, the flow pathswitching device 22 is arranged at the upstream side of the CO₂ recoverydevice 21 in the direction of flow of gas.

Further, the flow path switching device 22 communicates through anexhaust pipe connection passage 32 with the exhaust pipe 12. Inparticular, the exhaust pipe connection passage 32 communicates with theexhaust pipe 12 at the downstream side from the muffler 14 in thedirection of flow of exhaust gas. Therefore, the exhaust pipe connectionpassage 32 is configured so that exhaust gas can flow from the exhaustpipe 12 to the flow path switching device 22. In particular, since theexhaust pipe connection passage 32 communicates with the exhaust pipe 12at the downstream side from the muffler 14, relatively low temperatureexhaust gas flows into the exhaust pipe connection passage 32. Notethat, in the present embodiment, the exhaust pipe connection passage 32communicates with the exhaust pipe 12 at the downstream side from themuffler 14, but it may communicate with it upstream from the muffler 14and may also communicate with it upstream from the exhaust purificationdevice 13.

In addition, the flow path switching device 22 communicates through anoutside connection passage 33 with the outside of the vehicle 1. In thepresent embodiment, the outside connection passage 33 extends below theunderbody 2 of the vehicle 1 from the flow path switching device 22 tothe front of the vehicle 1 in the front-back direction of the vehicle 1.In particular, in the present embodiment, the inlet of the outsideconnection passage 33 is arranged in the engine compartment. Therefore,the outside connection passage 33 is configured to enable the outsideair around the vehicle 1 to flow from outside of the vehicle 1 to theflow path switching device 22. Note that, if able to make the air at theoutside of the vehicle 1 flow through the outside connection passage 33to the flow path switching device 22, the outside connection passage 33may be configured in any way. Therefore, for example, the inlet of theoutside connection passage 33 may be arranged at a lateral surface ofthe vehicle 1 (surface extending in front-back direction of vehicle 1).

Furthermore, the flow path switching device 22 communicates through aninside connection passage 34 with the inside of the vehicle 1. In thepresent embodiment, the inside connection passage 34 extends from theflow path switching device 22 toward the front of the vehicle 1 in thefront-back direction of the vehicle 1. In particular, in the presentembodiment, the inlet of the inside connection passage 34 is arrangednear a back seat of the vehicle 1 at the inside of the vehicle 1.Therefore, the inside connection passage 34 is configured so that it ispossible to make the air at the inside of the vehicle 1 flow from insideof the vehicle 1 to the flow path switching device 22. Note that, ifable to make the air at the inside of the vehicle 1 flow through theinside connection passage 34 to the flow path switching device 22, theinside connection passage 34 may be configured in any way. Therefore,for example, the inlet of the inside connection passage 34 may bearranged at the front of the inside of the vehicle 1.

The flow path switching device 22 is configured to switch the passagecommunicating with the communication path 31 among the exhaust pipeconnection passage 32, outside connection passage 33, and insideconnection passage 34. Therefore, the flow path switching device 22 isconfigured to switch the gas to be flowed into the CO₂ recovery device21 among the exhaust gas discharged from the engine body 11, the air atthe outside of the vehicle 1, and the air at the inside of the vehicle1. Specifically, the flow path switching device 22 is, for example, afour-way valve. In the present embodiment, the flow path switchingdevice 22 makes one passage among the exhaust pipe connection passage32, outside connection passage 33, and inside connection passage 34selectively communicate with the communication path 31. Therefore, inthe present embodiment, the flow path switching device 22 makes one ofthe exhaust gas discharged from the engine body 11, the air at theoutside of the vehicle 1, and the air at the inside of the vehicle 1,selectively flow into the CO₂ recovery device 21.

Note that, in the present embodiment, the flow path switching device 22is communicated with the exhaust pipe connection passage 32, outsideconnection passage 33, and inside connection passage 34. However, theflow path switching device 22 may also be configured to communicate withany two of these passages. Therefore, the flow path switching device isconfigured so as to switch the gas to be flowed into the CO₂ recoverydevice 21 between two gases among the exhaust gas discharged from theengine body 11, the air at the outside of the vehicle 1, and the air atthe inside of the vehicle 1.

Further, in the present embodiment, the flow path switching device 22 isconfigured so that one passage among the exhaust pipe connection passage32, outside connection passage 33, and inside connection passage 34 ismade to selectively communicate with the communication path 31. However,the flow path switching device 22 may also be configured to change theratio of the flow rate of gases flowing from a plurality of passages 32,33, 34 to the communication path 31. In this case, the flow pathswitching device 22 is configured as solenoid adjustment valves changingin opening area, which are provided at the passages 32, 33, and 34.

The suction pump 23 is provided at the exhaust passage 35 communicatedwith the CO₂ recovery device 21. The exhaust passage 35 is configured soas to discharge gas after recovery of CO₂ at the CO₂ recovery device 21into the atmosphere.

The suction pump 23 is configured so as to suck in gas from the CO₂recovery device 21. In other words, the suction pump 23 is configured soas to forcibly send gas from the exhaust pipe 12, inside of the vehicle1, and outside of the vehicle 1, through the flow path switching device22 to the CO₂ recovery device 21. Further, the suction pump 23 isconfigured so as to be able to change the output. If the output of thesuction pump 23 becomes larger, the flow rate of the gas flowing throughthe CO₂ recovery device 21 becomes greater.

In the present embodiment, the flow path switching device 22 and suctionpump 23 function as a flow rate control device controlling the flowrates of gases present in a plurality of different regions of thevehicle 1 (for example, at least any two of air at the outside of thevehicle 1, air at the inside of the vehicle 1, and exhaust gasdischarged from the engine body 11) into the CO₂ recovery device 21.

The cooling device 24 is provided in the exhaust pipe connection passage32 and cools the exhaust gas flowing through the exhaust pipe connectionpassage 32. Further, the cooling device 24 is not provided at theoutside connection passage 33 and inside connection passage 34.

The cooling device 24 is, for example, configured as a refrigerationcircuit having a compressor, condenser, expansion valve, and evaporator.In the cooling device 24, a refrigeration cycle is realized by arefrigerant circulating through these component parts. In particular,the evaporator performs heat exchange with the exhaust gas flowingthrough the exhaust pipe connection passage 32 either directly orindirectly through a medium so as to cool this exhaust gas. Thetemperature of the refrigerant at the refrigeration circuit falls to atemperature lower than the temperature of the atmosphere, therefore inthe present embodiment, the cooling device 24 can make the temperatureof the exhaust gas flowing into the CO₂ recovery device 21 fall to atemperature lower than the temperature of the atmosphere (ordinarytemperature).

Note that, the cooling device 24 does not necessarily have to beconfigured as a refrigeration circuit. The cooling device 24 may beconfigured in any way so long as cooling the exhaust gas flowing throughthe exhaust pipe connection passage 32. Therefore, for example, thecooling device 24 has a radiator of the vehicle 1 and is configured tocool the exhaust gas flowing through the exhaust pipe connection passage32 by the coolant cooled at the radiator.

Further, in the present embodiment, the cooling device 24 is provided atthe exhaust pipe connection passage 32. However, the cooling device 24may be provided at the communication path 31. In this case, the coolingdevice 24 can cool not only just the exhaust gas flowing through theexhaust pipe connection passage 32, but also all of the gases flowinginto the CO₂ recovery device 21. Further, the cooling device 24 may bearranged around the CO₂ recovery device 21 and configured to cool theCO₂ recovery device 21.

FIG. 3 is a view schematically explaining the configuration of the CO₂recovery system 20. As shown in FIG. 3, the CO₂ recovery system 20 hasan ECU 40. The ECU 40 has a processor for performing various processing,a memory storing a program and various information, and an interfaceconnected to various actuators and various sensors.

Further, the CO₂ recovery system 20 has various sensors. Specifically,the CO₂ recovery system 20 has an outside CO₂ concentration sensor 41,inside CO₂ concentration sensor 42, air-fuel ratio sensor 43, vehiclespeed sensor 44, and crank angle sensor 45.

The outside CO₂ concentration sensor 41 is provided at the outside ofthe vehicle 1 and detects the concentration of CO₂ in the air(atmosphere) at the outside of the surroundings of the vehicle 1. Theinside CO₂ concentration sensor 42 is provided at the inside of thevehicle 1 and detects the concentration of CO₂ in the air at the inside.The air-fuel ratio sensor 43 is provided at the exhaust pipe 12 anddetects the air-fuel ratio of the exhaust gas flowing through theexhaust pipe 12. The vehicle speed sensor 44 is provided around an axleof the vehicle 1 and detects the speed of the vehicle 1 based on therotational speed of the axle. The crank angle sensor 45 detects therotational angle of the crankshaft of the internal combustion engine 10.

Further, the ECU 40 is connected to various actuators of the CO₂recovery system 20 and controls these actuators. Specifically, the ECU40 is connected to the flow path switching device 22, suction pump 23,and cooling device 24 and controls them.

Flow of Gas at CO₂ Recovery System

In the CO₂ recovery system 20 configured as above, when the flow pathswitching device 22 is set so that the communication path 31communicates with the inside connection passage 34 and the suction pump23 is operating, the air at the inside of the vehicle 1 is supplied tothe CO₂ recovery device 21.

On the other hand, when the flow path switching device 22 is set so thatthe communication path 31 communicates with the outside connectionpassage 33 and the suction pump 23 is operating, the air at the outsideof the vehicle 1 is supplied to the CO₂ recovery device. Note that, whenthe flow path switching device 22 is set in this way, even if thesuction pump 23 is not being operated, if the vehicle 1 is running, airat the outside of the vehicle 1 is supplied to the CO₂ recovery device21.

Furthermore, when the flow path switching device 22 is set so that thecommunication path 31 communicates with the exhaust pipe connectionpassage 32 and the suction pump 23 is operating, the exhaust gas flowingthrough the exhaust pipe 12 is supplied to the CO₂ recovery device 21.Note that, when the flow path switching device 22 is set in this way,even if the suction pump 23 is not operating, only a small amount ofexhaust gas is supplied to the CO₂ recovery device 21.

Further, if the exhaust gas flowing through the exhaust pipe 12 is highin temperature, the exhaust gas is cooled by the cooling device 24before flowing into the CO₂ recovery device 21, by the cooling device 24being operated. For this reason, low temperature exhaust gas is made toflow to the CO₂ recovery device 21.

Control of CO₂ Recovery System

Next, referring to FIGS. 4 and 5, control at the CO₂ recovery system 20will be explained.

The concentration of CO₂ contained in the exhaust gas discharged fromthe engine body 11 is usually far higher than the concentration of CO₂in the air at the inside of the vehicle 1 and outside of the vehicle 1(atmosphere). Further, the amount of recovery of CO₂ at the CO₂ recoverydevice 21 per unit gas flow rate becomes greater, as the concentrationof CO₂ in the gas becomes higher.

Therefore, in the present embodiment, while the internal combustionengine 10 is operating, the flow path switching device 22 is set to theexhaust pipe connection position making the communication path 31communicate with the exhaust pipe connection passage 32. As a result,while the internal combustion engine 10 is operating, the exhaust gasflows through the exhaust pipe connection passage 32 to the CO₂ recoverydevice 21.

Further, the exhaust gas flowing through the exhaust pipe 12 is high intemperature. As explained above, if zeolite becomes high in temperature,it makes the adsorbed CO₂ be desorbed. Therefore, if high temperatureexhaust gas flows as is to the CO₂ recovery device 21, the CO₂ recoverydevice 21 becomes high in temperature and the recovered CO₂ is desorbedfrom the CO₂ recovery device 21.

Such a situation can occur even when a solid absorbent other thanzeolite or another method is used for recovering the CO₂. For example,even when using the physical absorption method or the chemicalabsorption method, the CO₂ is separated from the absorption solution byheating as explained above. Therefore, in such a case as well, if hightemperature exhaust gas flows into the CO₂ recovery device 21, therecovered CO₂ is desorbed from the CO₂ recovery device 21.

Therefore, in the present embodiment, when making exhaust gas flowthrough the exhaust pipe connection passage 32 into the CO₂ recoverydevice 21, the cooling device 24 is made to operate. Due to this,exhaust gas is cooled before flowing into the CO₂ recovery device 21.Accordingly, the CO₂ recovery device 21 is kept from becoming high intemperature and accordingly the recovered CO₂ is kept from beingdesorbed from the CO₂ recovery device 21.

On the other hand, while the internal combustion engine 10 is stopped,no exhaust gas is discharged from the engine body 11. Therefore, thereis no need to supply gas in the exhaust pipe 12 to the CO₂ recoverydevice 21. Therefore, in the present embodiment, while the internalcombustion engine 10 is stopped, the flow path switching device 22 isset to either of the outside connection position making thecommunication path 31 communicate with the outside connection passage 33or of the inside connection position making the communication path 31communicate with the inside connection passage 34.

Note that, if the flow path switching device 22 is configured so as tobe able to connect the communication path 31 to a plurality of passages,while the internal combustion engine 10 is stopped, the communicationpath 31 may be communicated with both of the outside connection passage33 and inside connection passage 34. Therefore, the flow path switchingdevice 22 is controlled so that while the internal combustion engine 10is stopped, at least one of the air at the outside of the vehicle 1 andthe air at the inside of the vehicle 1 flows into the CO₂ recoverydevice 21.

In particular, in the present embodiment, while the internal combustionengine 10 is stopped, the flow path switching device 22 is controlled sothat the air with the higher CO₂ concentration among the air at theoutside and the air at the inside, is supplied to the CO₂ recoverydevice 21. Therefore, when the CO₂ concentration in the air at theoutside is high, the flow path switching device 22 is set to the outsideconnection position, while when the CO₂ concentration in the air at theinside is high, the flow path switching device 22 is set to the insideconnection position. As a result, the CO₂ recovery device 21 is suppliedwith air with a high CO₂ concentration, and accordingly the recoveryefficiency of the CO₂ can be raised. On the other hand, when theinternal combustion engine 10 is stopped and the CO₂ concentration inthe air at the outside and the CO₂ concentration in the air at theinside are substantially equal, the flow path switching device 22 is setto the outside connection position.

Next, referring to FIG. 4, control of the output of the suction pump 23will be explained. FIG. 4 is a view showing a relationship between pumpwork performed by a suction pump 23 and an amount of CO₂ reduction. Theamount of CO₂ reduction shows the amount of CO₂ recovered by the CO₂recovery device 21 per unit time minus the amount of CO₂ correspondingto the energy required for driving the pump. Therefore, it can be saidthat the larger the amount of CO₂ reduction, the more efficiently CO₂ isrecovered at the CO₂ recovery device 21. The solid line in the figureshows the relationship when the CO₂ concentration in the gas supplied tothe CO₂ recovery device 21 is high, while the broken line in the figureshows the relationship when this CO₂ concentration is low.

As shown in FIG. 4, when the pump work of the suction pump 23 is small,the flow rate of gas flowing into the CO₂ recovery device 21 is small,therefore the amount of CO₂ recovery at the CO₂ recovery device 21 issmall. As a result, in a region with a small pump work, the amount ofCO₂ reduction is small. On the other hand, when the pump work of thesuction pump 23 is large, the flow resistance at the CO₂ recovery device21 is large and the flow rate of gas flowing through the CO₂ recoverydevice 21 is small with respect to the magnitude of the pump work. As aresult, even in a region with large pump work, the amount of CO₂reduction is small. On the other hand, in a region with an intermediateextent of the magnitude of the pump work, the flow rate of the gasflowing into the CO₂ recovery device 21 is large and the flow resistanceis small, therefore the amount of CO₂ reduction is great.

In this regard, the magnitude of the pump work where the amount of CO₂reduction is maximum, changes according to the CO₂ concentration in thegas. In the illustrated example, when the CO₂ concentration is high, theamount of CO₂ reduction is maximum when the pump work is W1. On theother hand, when the CO₂ concentration is low, the amount of CO₂reduction is maximum when the pump work is W2.

Therefore, in the present embodiment, the output of the suction pump 23is set based on the CO₂ concentration in the gas supplied to the CO₂recovery device 21. Specifically, if there is the relationship such asshown in FIG. 4, when the CO₂ concentration is relatively high, theoutput of the suction pump 23 is controlled so that the pump work isrelatively low. By controlling the suction pump 23 in this way, it ispossible to efficiently recover the CO₂ at the CO₂ recovery device 21.

Further, in the present embodiment, when the flow path switching device22 is set to the outside connection position, the suction pump 23 iscontrolled so that its output becomes lower as the running speed of thevehicle 1 becomes faster.

In this regard, as explained above, when the flow path switching device22 is set to the outside connection position, if the vehicle 1 isrunning, outside air is forcibly made to flow to the outside connectionpassage 33. Therefore, even if the output of the suction pump 23 is madesmaller, a large amount of air can be supplied to the CO₂ recoverydevice 21. Therefore, it is possible to reduce the pump work at thesuction pump 23 while maintaining the amount of recovery of CO₂ at theCO₂ recovery device 21.

FIG. 5 is a flow chart showing a control routine in control in the CO₂recovery system 20. The illustrated control routine is performed everycertain time interval.

First, at step S11, the operating state of the internal combustionengine and the CO₂ concentrations in the gases at a plurality ofdifferent regions of the vehicle 1 are detected, based on the outputs ofvarious sensors. Next, at step S12, it is judged if the internalcombustion engine 10 is being operated. For example, if the currentengine rotational speed calculated based on the output of the crankangle sensor 45 is zero, it is judged that the internal combustionengine 10 has stopped. When it is not zero, it is judged that theinternal combustion engine 10 is being operated. At step S12, if it isjudged that the internal combustion engine 10 is being operated, thecontrol routine proceeds to step S13.

At step S13, the flow path switching device 22 is set to the exhaustpipe connection position. Next, at step S14, the output of the suctionpump 23 is set based on the CO₂ concentration in the gas flowing throughthe exhaust pipe connection passage 32 to the CO₂ recovery device 21.The CO₂ concentration is calculated based on the output of the air-fuelratio sensor 43. As the air-fuel ratio of the air-fuel ratio sensor 43is larger (leaner), the calculated CO₂ concentration is smaller. Next,at step S15, the cooling device 24 is operated and the temperature ofthe exhaust gas flowing into the flow path switching device 22 islowered.

On the other hand, if, at step S12, it is judged that the internalcombustion engine 10 is not operating, the control routine proceeds tostep S16. At step S16, it is judged if the CO₂ concentration at theinside of the vehicle 1 is higher than the CO₂ concentration at theoutside of the vehicle 1. The CO₂ concentration at the inside of thevehicle 1 is detected by the inside CO₂ concentration sensor 42, whilethe CO₂ concentration at the outside of the vehicle 1 is detected by theoutside CO₂ concentration sensor 41.

If, at step S16, it is judged that the CO₂ concentration at the insideof the vehicle 1 is higher than the CO₂ concentration at the outside ofthe vehicle 1, the control routine proceeds to step S17. At step S17,the flow path switching device 22 is set to the inside connectionposition. Next, at step S18, the output of the suction pump 23 is setbased on the CO₂ concentration at the inside of the vehicle 1.Accordingly, the flow rate of air at the inside of the vehicle 1 flowinginto the CO₂ recovery device 21 is controlled based on the CO₂concentration at the inside of the vehicle 1. Next, at step S19, thecooling device 24 is stopped.

On the other hand, if, at step S16, it is judged that the CO₂concentration at the inside of the vehicle 1 is equal to or greater thanthe CO₂ concentration of the outside of the vehicle 1, the controlroutine proceeds to step S20. At step S20, the flow path switchingdevice 22 is set to the outside connection position. Next, at step S21,the output of the suction pump 23 is set based on the CO₂ concentrationat the outside of the vehicle 1 and the speed of the vehicle 1.Accordingly, the flow rate of the air at the outside of the vehicle 1flowing into the CO₂ recovery device 21 is controlled, based on the CO₂concentration at the outside of the vehicle 1 and the speed of thevehicle 1. The speed of the vehicle 1 is detected by the vehicle speedsensor 44. Next, at step S22, the cooling device 24 is stopped.

Second Embodiment

Next, referring to FIG. 6, the CO₂ recovery system according to a secondembodiment will be explained. The configuration and control of the CO₂recovery system according to the second embodiment are basically similarto the configuration and control of the CO₂ recovery system according tothe first embodiment. Below, the parts different from the firstembodiment will be focused on in the explanation.

FIG. 6 is a view schematically explaining the configuration of a CO₂recovery system 20 according to the second embodiment. As shown in FIG.6, the CO₂ recovery system 20 has a discharge path switching device 25and driver monitor camera 46, in addition to the components in the firstembodiment.

The discharge path switching device 25 communicates through the exhaustpassage 35 with the CO₂ recovery device 21. Therefore, the gasdischarged from the CO₂ recovery device 21 flows into the discharge pathswitching device 25. Further, the discharge path switching device 25communicates through the release passage 36 to the outside of thevehicle 1 and communicates through the return passage 37 to the insideof the vehicle 1.

The discharge path switching device 25 makes one passage among therelease passage 36 and the return passage 37 be selectively communicatedwith the exhaust passage 35. Therefore, the discharge path switchingdevice 25 selectively discharges the gas discharged from the CO₂recovery device 21 to one of the outside and inside of the vehicle 1.

The driver monitor camera 46, for example, is arranged on the topsurface of a steering column cover and captures an image of the face ofthe driver. The output signals of the driver monitor camera 46 is inputto the ECU 40.

The ECU 40 calculates the degree of awakeness of the driver based on theimage of the face of the driver sent from the driver monitor camera 46.The degree of awakeness of the driver is, for example, calculatedconsidering the degrees of opening of the eyes of the driver, theorientation of the face of the driver, movement of the eyes and face ofthe driver, etc. Alternatively, the degree of awakeness of the driver iscalculated using a neural network learned based on the image of the faceof the driver. A low degree of awakeness of the driver expresses majorsleepiness of the driver, a drop in concentration, etc. Note that, thedegree of awakeness of the driver may also be calculated based onequipment other than the driver monitor camera.

Inn general, it is known that if in an environment of a high CO₂concentration, drowsiness is induced and concentration is decreased.That is, when the degree of awakeness of the driver is low, the cause isbelieved to be a high CO₂ concentration at the inside of the vehicle 1.

Therefore, in the present embodiment, when the degree of awakeness ofthe driver calculated based on the output of the driver monitor camera46 is lower than a predetermined reference value, the flow pathswitching device 22 is set to the inside connection position. Due tothis, the air at the inside of the vehicle 1 is supplied to the CO₂recovery device 21. In addition, the discharge path switching device 25is set to a return position making the exhaust passage 35 communicatewith the return passage 37. Due to this, the gas discharged from the CO₂recovery device 21 is returned to the inside of the vehicle 1. As aresult, gas from which CO₂ has been recovered at the CO₂ recovery device21 and at which the CO₂ concentration has been lowered, is returned tothe inside of the vehicle 1. Therefore, it is possible to keep the CO₂concentration at the inside of the vehicle 1 low.

FIG. 7 is a flow chart showing a control routine in control in the CO₂recovery system 20. The illustrated control routine is performed everycertain time interval.

First, at step S31, the degree of awakeness of the driver is calculatedat the ECU 40 based on the output of the driver monitor camera 46, etc.Next, at step S32, it is judged if the degree of awakeness detected atstep S31 is lower than a predetermined reference value, that is, if theconcentration of the driver is falling. If, at step S32, it is judgedthat the degree of awakeness of the driver is lower than the referencevalue, the control routine proceeds to step S33.

At step S33, the discharge path switching device 25 is set to the returnposition. Next, at step S34, the flow path switching device 22 is set tothe inside connection position. Next, at step S35, the output of thesuction pump 23 is set based on the CO₂ concentration at the inside ofthe vehicle 1. Accordingly, the flow rate of air at the inside of thevehicle 1 flowing to the CO₂ recovery device 21 is controlled based onthe CO₂ concentration at the inside of the vehicle 1. Next, at step S36,the cooling device 24 is stopped.

On the other hand, if, at step S32, it is judged that the degree ofawakeness of the driver is equal to or greater than the reference value,the control routine proceeds to step S37. At step S37, the dischargepath switching device 25 is set to a release position making the exhaustpassage 35 communicate with the release passage 36. Next, at step S38,the normal control shown in FIG. 5 is performed.

Above, preferred embodiments according to the present invention wereexplained, but the present invention is not limited to these embodimentsand may be modified and changed in various ways within the language ofthe claims.

REFERENCE SIGNS LIST

-   1 vehicle-   10 internal combustion engine-   11 engine body-   12 exhaust pipe-   20 CO₂ recovery system-   21 CO₂ recovery device-   22 flow path switching device-   23 suction pump-   24 cooling device

The invention claimed is:
 1. A CO₂ recovery system used in a vehicle,comprising: a CO₂ recovery device recovering CO₂ contained in inflowinggas; and a flow rate control device controlling flow rates of gasespresent in a plurality of different regions of the vehicle flowing intothe CO₂ recovery device, wherein the gases present at the plurality ofdifferent regions include at least any two among air at an outside ofthe vehicle, air at an inside of the vehicle, and exhaust gas dischargedfrom a body of an internal combustion engine of the vehicle, the flowrate control device has a switching device arranged at an upstream sideof the CO₂ recovery device in a direction of flow of the gas and a pumpforcibly sending gases from a plurality of different regions through theswitching device to the CO₂ recovery device, the switching deviceswitches the gas to be flowed to the CO₂ recovery device among the gasespresent in the plurality of different regions, the vehicle has aninternal combustion engine having the body of the internal combustionengine and an exhaust passage through which exhaust gas discharged fromthe body of the internal combustion engine flows, the gases present atthe plurality of different regions include exhaust gas discharged fromthe body of the internal combustion engine, and the switching devicecommunicates with the exhaust passage so that exhaust gas can flow tothe switching device from the exhaust passage.
 2. The CO₂ recoverysystem according to claim 1, wherein the flow rate control devicecontrols the flow rate of air at the outside of the vehicle flowing intothe CO₂ recovery device, based on a CO₂ concentration in the air at theoutside of the vehicle.
 3. The CO₂ recovery system according to claim 1,wherein the flow rate control device controls the flow rate of air atthe inside of the vehicle flowing into the CO₂ recovery device, based ona CO₂ concentration in the air at the inside of the vehicle.
 4. The CO₂recovery system according to claim 1, wherein a first connection passagecommunicating the exhaust passage with the switching device is providedwith a cooling device cooling the gas, and a second connection passagecommunicating an outside of the vehicle with the switching device and athird connection passage communicating an inside of the vehicle with theswitching device are not provided with cooling devices.
 5. The CO₂recovery system according to claim 1, wherein a communication pathcommunicating the switching device with the CO₂ recovery device isprovided with a cooling device cooling gas flowing through thecommunication path.
 6. The CO₂ recovery system according to claim 1,wherein the flow rate control device controls the flow rate of theexhaust gas, which is discharged from the body of the internalcombustion engine, flowing into the CO₂ recovery device, based on theCO₂ concentration in the exhaust gas flowing through the exhaustpassage.
 7. The CO₂ recovery system according to claim 1, wherein theflow rate control device is controlled so that when the internalcombustion engine is stopped, at least one of air at the outside of thevehicle and air at the inside of the vehicle, flows into the CO₂recovery device.
 8. The CO₂ recovery system according to claim 1,wherein when the flow rate control device is controlled so that air atthe outside of the vehicle flows into the CO₂ recovery device, the pumpis controlled so that an output of the pump decreases, as the a runningspeed of the vehicle becomes faster.
 9. The CO₂ recovery systemaccording to claim 1, wherein the system further comprises an awakenessdegree detection device for detecting a degree of awakeness of a driver,the CO₂ recovery device is configured to be able to return gasdischarged from the CO₂ recovery device to the inside of the vehicle,and when a degree of awakeness of the driver is lower than apredetermined threshold value, the flow rate control device iscontrolled so that the air at the inside of the vehicle flows into theCO₂ recovery device and the gas discharged from the CO₂ recovery deviceis returned to the inside of the vehicle.